<i>Overosaurus paradasorum</i> gen. et sp. nov. , a new sauropod dinosaur (Titanosauria: Lithostrotia) from the Late Cretaceous of Neuquén, Patagonia, Argentina

Abstract

A new lithostrotian sauropod, the small-sized Overosaurus paradasorum n. gen et sp. from the Anacleto Formation (Campanian, Late Cretaceous, Neuquén Group, Patagonia, Argentina) is here described. The specimen (MAU-Pv-CO-439) consists of a fully articulated vertebral series from the 10 th cervical to the 20 th caudal vertebra, the last cervical ribs, several dorsal ribs in articulation with their respective vertebrae, the complete right ilium and fragments of the left ilium. Overosaurus paradasorum is diagnosed by a unique combination of characters that includes (1) posterior cervical vertebrae with long pre-and postzygapophyses that project beyond the anterior and posterior borders of the centrum, respectively, (2) postspinal lamina absent in all dorsal neural spines, (3) wide and massive 9 th and 10 th caudal centra that are slightly excavated laterally and have relatively flat ventral surfaces, (4) laminar projection on the posterior border of the second and third dorsal rib, (5) ilium proportionally shorter anteroposteriorly and taller dorsoventrally than in other lithostrotians, and (6) the preacetabular process of the ilium strongly deflected laterally and with a ventrolaterally tapering end. Analysis of the phylogenetic relationships of Overosaurus places it within the Aeolosaurini, as the sister taxon of a monophyletic group formed by Aeolosaurus rionegrinus, A. maximus, Gondwanatitan faustoi and Pitekunsaurus macayai. Overosaurus is a new representative of a highly diversified assemblage of Campanian lithostrotians from Patagonia that includes both Aeolosaurini and saltasaurids (e.g. Saltasaurus, Neuquensaurus)-this small new taxon falls within the low end of the size spectrum represented by these Late Cretaceous sauropods.

An articulated cervical series of Alamosaurus sanjuanensis Gilmore, 1922 (Dinosauria, Sauropoda) from Texas: new perspective on the relationships of North America's last giant sauropod

“…In this regard BIBE 45854 again stands in marked contrast to the saltasaurines Saltasaurus and Neuquensaurus, taxa in which the cervical postzygapophyses project far posterior beyond their respective centra. The cervical postzygapophyses also reach to or beyond the posterior rim of the centra in other titanosaurs, such as Isisaurus colberti, Rapetosaurus krausei and Overosaurus paradasorum (Jain & Bandyopadhyay 1997;Curry Rogers 2009;Coria et al 2013). The presence of short postzygapophyses in BIBE 45854 more closely resembles the condition in Dreadnoughtus schrani, some posterior cervical vertebrae of Malawisaurus dixeyi, Trigonosaurus pricei, brachiosaurids, Sauroposeidon proteles and TMM 43621-1 (Wedel et al 2000a, b;Lehman & Coulson 2002;Campos et al 2005;Gomani 2005;Lacovara et al 2014).…”

“…The ventral surfaces on all the vertebrae lack ventral keels and defined fossae (Fig. 5), in contrast to the fossae and keels seen in the posterior cervical vertebrae of Overosaurus paradasorum (Coria et al 2013). The ventral surfaces of the centra are marked by numerous small foramina, possibly mirroring the somphospondylus internal structure of the vertebrae.…”

The first evidence of osteomyelitis in a sauropod dinosaur

“…,b; Coria et al . ; García & Salgado ). Despite this large sample, reports of pathologies have proven elusive, with exception of Gallina's () report on Bonitasaura salgadoi .…”

A Gigantic, Exceptionally Complete Titanosaurian Sauropod Dinosaur from Southern Patagonia, Argentina

“…The majority of titanosaurs for which the dorsal series is completely known (e.g., Futalognkosaurus , Rapetosaurus , Trigonosaurus , Overosaurus ) possess ten vertebrae in this region3183964; with 11 dorsal vertebrae, Opisthocoelicaudia is the only known exception in this regard35. We therefore assume that ten dorsal vertebrae were present in Dreadnoughtus .…”